OTTAWA - A decades-old cat sanctuary nestled behind Canada's Parliament buildings is heading towards a quiet end as its feline population slowly shrinks.

The sanctuary — a hold-over from the days when cats worked as mousers on Parliament Hill — was once home to as many as 30 strays, but spaying and neutering has reduced their ranks to just four today.

"There were kittens born here, the last ones probably 10 to 15 years ago," said Brian Caines, a sanctuary volunteer and former public servant.

"So now, we're down to four."

In 1955, more modern, chemical-based rodent control methods put the cats out of work, but they never left the hill. Volunteers like Irene Desormeaux, who died in 1987, took it upon themselves to take care of the animals.

In the 1980s, Rene Chartrand became known as "the cat man" after taking over for Desormeaux, building an elaborate wooden shelter for the animals and adopting the role as their full-time volunteer caregiver.

Chartrand cared for the cats without government help, relying entirely on public donations, until retiring in November 2008. He does not run the shelter any longer due to health reasons.

The structures have since been updated and replaced with newer ones to provide the cats shelter and some warmth from Ottawa's bitter winters.

Caines said he got involved with the sanctuary when he worked for the Privy Council in the 1990s. The eventual decline of the cat population is a good thing, he said, since Parliament Hill isn't really the best place for them.

"People ask why we don't get cats and drop them off here, to replenish. I know that any animal rights group would certainly take exception to that," Caines said.

"They've got a great life, there's no question about it, people are caring for them. But they are living outdoors and winters are very hard on them."

Prime Minister Stephen Harper, a known cat lover, spoke to a volunteer at the sanctuary once, Caines said. Harper's wife Laureen has also been in touch with the sanctuary, and MPs are known to drop by from time to time.

The sanctuary is run by about seven volunteers, who visit it daily to make sure the cats are fed. The volunteers buy the wet food while a Quebec company donates the dry food.

"We used to have a donation box here, but two years ago we took it down because as the cats' numbers were going down, we had collected enough money over time," Caines said.

No one knows for sure where the cats came from, although one popular — if unconfirmed — story has them descended from cats brought to the area by Colonel John By, the founder of Ottawa and the Rideau Canal.

Caines said he enjoys the story, but has no idea if it's true.

"It's a wonderful spot and I'll certainly miss it when it does go," he said.